Process for direction-selective orientation of a passive safety device

Abstract

A process and a mechanism for the direction-selective triggering of a passive safety device in a vehicle, with at least two acceleration transducers, where the acceleration transducers have directional sensitive axes and these have actual instantaneous orientations and are aligned in different, preferably specified reference orientations and there is an angle tolerance between the reference and the instantaneous orientations of the sensitive axes. An evaluation device is provided to correct the angle tolerance, comprising an electronic circuit which converts the signals (am 1, am 2, . . . am n) coming from the acceleration transducers to corrected output signals (a(I), a(II), . . . a(n)), which are linear combinations of the incoming signals with adjustable factors c ij : ##EQU1## This can lessen the expense of production compared to familiar mechanisms, without simultaneously reducing the measuring accuracy of the mechanism. In particular, if acceleration transducers with considerably higher angle tolerances are used, it is possible to achieve a higher level of measuring accuracy and sensitivity can be equalized and angle tolerance offset simultaneously in a single, inexpensive operation.

What is claimed is: 
     
       1. A process for the direction-selective triggering of a passive safety device in a vehicle, particularly relevant to an airbag system, where at least two acceleration transducers and one evaluation device are provided, to pick up the signals coming from the acceleration transducers, processes them and if the vehicle is involved in a crash, make output signals available to trigger the passive safety device, and   the acceleration transducers have directional sensitive axes, where the sensitive axes have actual instantaneous orientations and are aligned in different and preferably specified reference orientations and there is an angle tolerance between the reference and instantaneous orientations of the sensitive axes wherein, there is angle correction, by converting the n signals (am 1, am 2, . . . am n) coming from n≧2 acceleration transducers to n output signals (a(I), a(II), . . . a(n)), where the output signals (a(I), a(II), . . . a(n)) are linear combinations of incoming signals (am 1, am 2, . . . am n) with adjustable factors (c ij ): ##EQU6##     
     
     
       2. A mechanism for direction-selective triggering of a passive safety device in a vehicle according to Patent claim 1, wherein the evaluation device comprises an electronic circuit which converts n signals (am 1, am 2, . . . am n) coming from n≧2 acceleration transducers to n output signals (a(I), a(II), . . . a(n)), where the output signals (a(I), a(II), . . . a(n)) are linear combinations of the incoming signals (am 1, am 2, . . . am n) with adjustable factors (c ij ): 
     
     
       3. A mechanism according to claim 2, wherein the electronic circuit comprises at least one analog/digital converter to digitize n signals (am 1, am 2, . . . am n) coming from the acceleration transducers and a microprocessor to convert the digitized signals to n output signals (a(I), a(II), . . . a(n)). 
     
     
       4. A mechanism according to claim 3, wherein the microprocessor is linked to a memory unit, in which the adjustable factors (c ij ) are stored as digitized data. 
     
     
       5. A mechanism according to claim 4, wherein the memory unit contains one or more EEPROM units. 
     
     
       6. A mechanism according to claim 2, wherein factors c ij  can be adjusted by tunable ohmic resistors. 
     
     
       7. A process to determine factors c ij  for a mechanism according to claim 1, wherein there are the following steps to the process: sequential impression of n known acceleration signals in n different directions to n acceleration transducers and measurement of the resulting n ×n output signals (a(I) 1 , a(I) 2 , . . . a(I) n  ; a(II) 1 , a(II) 2 , . . . a(II) n  ; . . . ; a(n) 1 , a(n) 2 , . . . a(n) n ) determination of factors c ij  from the measured output signals in accordance with ##EQU7##  where {c ij  } is an n×n matrix constructed from factors (c ij ) and a correction matrix {R ij  } contains the specified theoretical values which can ideally be expected from the known acceleration signals.   
     
     
       8. Process according to claim 7, wherein correction matrix {R ij  } is the unit matrix {E}, if the n known acceleration signals in n different directions are orthogonal and all the amplitudes of the acceleration signals have a specified unit value.